Mount Disappointment is a

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher t ...

in the

San Gabriel Mountains The San Gabriel Mountains () are a mountain range located in Los Angeles and San Bernardino counties, California, United States. The mountain range is part of the Transverse Ranges and lies between the Los Angeles Basin and the Mojave Desert ...

Los Angeles County, California Los Angeles County, officially the County of Los Angeles and sometimes abbreviated as LA County, is the List of United States counties and county equivalents, most populous county in the United States, with 9,663,345 residents estimated in 202 ...

with a summit elevation of 5,963+ feet (1,818+ m). It was named "Disappointment" in 1894 when

USGS The United States Geological Survey (USGS), founded as the Geological Survey, is an government agency, agency of the United States Department of the Interior, U.S. Department of the Interior whose work spans the disciplines of biology, geograp ...

surveyors in the

Wheeler Survey The Wheeler Survey, carried out in 1872-1879, was one of the "Four Great Surveys" conducted by the United States government after the Civil War primarily to document the geology and natural resources of the American West. Supervised by First Lieu ...

sighted it from the

Santa Susana Mountains The Santa Susana Mountains are a transverse range of mountains in Southern California, north of the city of Los Angeles, in the United States. The range runs east-west, separating the San Fernando and Simi valleys on its south from the Santa ...

, believing it to be the highest point in the immediate area, decided to use it as their next triangulation point. When they reached the summit, however, they discovered that San Gabriel Peak half a mile (0.8 km) to the east was higher and it was a disappointment so they moved there instead. A Nike missile site was located there in 1955 and the summit was flattened to accommodate it. The missile site was abandoned in 1965. The mountain top is now an important telecommunications site for both commercial and government organizations.

References

Mountains of Los Angeles County, California San Gabriel Mountains U.S. Army Nike sites Mountains of Southern California {{LosAngelesCountyCA-geo-stub